Railway signaling system



INVENTOR kn/2 ,l2/@Mmmm y mm 7 Sheets-Sheet l HIJ ATTORNEY R. R. KEMMERER RAILWAY SIGNALING SYSTEM Flled bec 28 1940 July 14, 1942. R. R. KMMERER 2,289;842

' RAILWAY SIGNALING SYSTEM Filed Deo. 28', 1940 7 Sheets-Sheet 2 A) l VENTOR BY a P Wl- L L j l HIJ' ATTORNEY 'I R. R. KEM'Mr-:RER

RAILWAY SIGNALING SYSTEM July 14, 1942.

Filed Dec. 28, 1940 7 Sheets--Sheet 5 INVENTOR av/mmemp BYR HIS ATTORNEY July 14, 1942. I AR. R. KEMMERER 2,289,842

` RAILWAY SIGNALING SYSTEM Filed Dec. 28, 1940 7 Sheng-sheet 4 ,mf 2 r 24151' i 12T 11T AAAAA INVENTOR HS ATTORNEY July 14, 1942.`

R. R. KEMMERER RAILWAY SIGNALING SYSTEM 7 Sheets-Sheet 5 INVENTOR HIS ATTORNEY Filed Deo. 28, 1940 Ju1y"14, 1942.

IR. R. KEMMERER RAILWAY S IGNALING SYSTEM Filed Deo. 28, 1940' 7 Sheets-Sheet 6 INVENTOR HIS' ATTORNEY July 14, `1 942.

R. R. KEMMr-:RER 2,289,842

RAILWAY SIGNALING SYSTEM Filed Dec. 28, 1940 v 7 Sheets-Sheet 7 INVENTOR .HIS ATTORNEY Patented July 14, 1942 RAILWAY SIGNALING SYSTEM Ralph R. Kemmerer, Swissvale, Pa., assignor to The Union Switch &Signal Company, Swissvale, Pa., a corporation of Pennsylvania Application December 28, 1940, Serial No. 372,027

11 Claims.

My invention relates to a railway signaling system of the double overlap type adapted for use on a stretch of railroad track over which trains normally move in both directions. The system includes wayside signals which are controlled over line wires which parallel the track stretch.

t is an object ofmy invention to provide an improved signalingsystem of the type described which is arranged so that` the number of line wires required is reduced to the smallest possible number.

A further object of my invention is to provide a signaling system of the type described which is arranged to reduce to a minimum the possibility that a signal will falsely display a proceed indication in the event there is a cross between the line wires.

Another object of my invention is to provide new and improved means for overlapping the control of the signals in a track stretch and for approach controlling the circuits of the lamps of these signals.

A further object of my invention is to provide a signaling system employing signals of the semaphcre type, the system incorporating improved means for energizing the holding coils which are employed in signals of this type.

A further object of my invention is to provide an improved railway signaling system.

Other objects of the invention and features of novelty will be apparent from the following description taken in connection with the accompanying drawings.

I shall describe three forms of railway signaling systems embodying my invention, and shall then point out the novel features thereof in claims.

In the drawings Figs. l, la and 1b taken together form a diagram showing a track stretch equipped with signaling apparatus embodying my invention,

Fig. 2 is a fragmentary view showing a modiiication which I may employ, and

Figs. 3, 3a and 3b taken together form a diagram showing a track stretch equipped with another form oi signaling systeml provided by my invention. y

Referring to Figs. 1, la and 1b of the drawings, there is shown therein a stretch of railroad track having track rails I and 2 over which traiic moves in both directions. The track rails are divided by insulated joints into track sections in the customary manner. To 'facilitate description of the equipment it will be assumed that the left-hand end thereof is west and that the rightv hand end thereof is east.

Accordingly train movements from right to left are westbound and train movements from left to right are eastbound.

The track stretch includes passing sidings which are located at appropriate intervals and permit traffic to be diverted from the main track under the customary control of switches, not shown. Two such passing sidings are shown and are designated M and N. n

The equipment associated with each of the passing sidings is the same as that associated with the other sidings, while the equipment for the track stretches between sidings is similar.

For purposes of explanation of the voperation of the equipment the signals have been numbered starting from a point at the east end of each passing siding. The signals governing westbound traiiic are identified by odd numbers, while the signals governing eastbound traino are identied by even numbers. The signals starting at the east end of passing siding N are numbered in a series beginning with IW, while the signals starting at the east end of passing siding M are num- A bered in a series starting with 2IW. The reference characters for the westbound signals include the sufx W, while the reference characters for the eastbound signals include the suffix E. The track sections are numbered IT, 2T, 3T,

A etc., in a series corresponding to that of the signals.

in the drawings.

The signals are shown as being of the color light type, while each of the signals has associated therewith a suitable source of energy the terminals of which are designated (-1-) and While color light signals are shown the invention is not limited to the use of signals of this type and any desired form of signals may be employed.

Each of the track sections is provided with a track circuit including a track battery connected across the section rails at one end of the section, and a track relay, designated TR with a suitable prex, connected across the section rails at the other end of the section.

For the purpose of controlling the signals a number of line circuits are provided which are controlled by contacts o f the track relays. These line circuits are employed to determine the indications displayed by the signals and also to govern lighting of the lamps of the signals.

In order that the same line circuits may be employed to control both the east and the westbound signals means is provided for supplying alternating current energy to certain of thesey line circuits at one end, and for supplying direct current energy to the other end of the same line circuit, while these circuits have energized therefrom relays which are responsive only to one type of energy.

The system has been designed for use where a commercial source of alternating current is not available, and it is contemplated that the alternating current energy employed in the system will be generated locally by tuned reed alternators or similar devices. In order to reduce the number of these devices required the Vsystem has been arranged so that wherever possible the alternating current energy for several line circuits is supplied from one alternator.

In order to simplify the disclosure the tuned alternators have not been shown in the' drawings, while the primary windings of the line circuit supply transformers are shown as connected to terminals BX and CX of a-source of alternating current. This source may be a tuned alternator or it may be a commercial sourceof current, if such is available.

Each of the passing sidings has associated therewith line circuits I and II for energizing relays which control the signalsat the ends of the siding.

In addition, each siding has extending from the eastern or right end thereof a line circuit III over which energy is supplied 4,to a -relay which controls the westbound approach -signal to the siding.

Likewise, each siding has extending from the western or left end thereof aline circuit IV over which energy is supplied to a `relay which controls the eastbound approach signal tothe passing siding.

Each passing siding also has extending from the east or right end thereof a line circuit V which extends to the westbound distant signal for the passing siding and over which'direct eurrent energy `is supplied to control the westbound distant signal for the passing ysiding and to also control lighting of th'e intermediate eastbound signal. In addition, alternating current is supplied over this line circuit to control the eastbound signals at the end of the passing siding.

In similar manner a line circuit VI extends fromV the left or west end of each passing siding to the first eastbound signal east of the adjacent passing siding to the west. Alternating current energy is supplied over this circuit to Acontrol certain of the eastbound signals,while direct current is also supplied over this vcircuit toV control lighting of certain of the eastbound signals, and to also control the indications displayed' by certain of the westbound signals.

A line circuit VII is also provided and controls the indication displayed by a westbound signal, while it also controls lighting of one of th'e eastbound signals. A line circuit VIII -is also -employed and controls the indication displayed by one of the eastbound signals.

Where both alternating and direct current is supplied over the same line circuit, a reactor RA is connected in series with the circuit to prevent flow of alternating current energy through the battery from which direct current energy is supplied to the circuit, while the direct current relays which are connected to the line circuit have windings of such' high impedance as to substantially prevent flow of alternating current energy therein. In addition, these circuits have resistances RB connected in series therewith to limit the iiow of direct current in the secondary 7 windings of the transformers from which alternating current energy is supplied to the circuits. Likewise, the circuits for connecting the relays responsive to alternating current across the line circuits have resistances included in series therewith to limit the flow of direct current in the circuits of the primary windings of the transformers through which energy is supplied to these relays.

The equipment is shown in the condition which it assumes when the track stretch is vacant. At this time all of the track relays are picked up so that the various line circuits are complete and the relays energized therefrom are all picked up and condition the various signals wh'en lighted to display green or clear indications. At this time, however, as all of the relays are picked up, the .circuits of the signal lamps are interrupted and all of the signals are dark.

Operation of the equipment on movement of an veastbcumi train through the track 'stretch When a train moving from left to right advances a predetermined distance beyond the passing siding west of the siding M, it releases a track relay, not shown, and thereby cuts off the supply of energy from a battery, not shown, to the line circuit VI associated with siding M, as will be clearly understood by reference to the corresponding equipment associated With passing siding N.

On interruption of the supply of direct current energy to the line circuit VI the relays 25WH and 23WI-I release vand establish the circuits for supplying energy to the lamps of the signals 25E and 24E.

At this time relay ZED is picked up by current from transformer IVTT supplied over the line circuit IV and through the transformer and rectifier associated with the relay. As relay 25ED is picked up, the circuit of the green lamp of signal ZE is established and this lamp is lighted to indicate that the track stretch in advance is vacant.

As the track stretch is assumed to be vacant, relay ZQEH is picked up by direct current energy supplied over line circuitJ I, while relay ZED is picked up by direct currentI energy supplied over line circuit II. As the relays MEI-I and ZGED are picked up, the circuit of the green lamp of signal 24E is established, and this lamp is lighted to indicate that the track stretch in advance is vacant.

As the eastbound train proceeds through the track stretch, the westbound signals in advance of the train are conditioned to display appropriate signals when lighted s0 that two trains traveling in opposite directions will not collide head-on. This part of the operation of the system will be considered in detail below.

When the train under consideration advances into section ZT, track relay 24TH releases and interrupts line circuits I, IV and VI so that relay ZBED releases and conditions the signal 23E to display its yellow indication.

On release of track relay MTR the supply of alternating current energy to the line' circuit I is cut off and relay 2 lW H releases and establishes the circuit of the lamps of signal 22E. At this time relay 22EH is supplied with energy from transformer VTT over line circuit V so that its contact establishes the circuit of the green lamp of signal 22E and this lamp is lighted.

In addition, as a result of release of relay IIWI-I, the signal 2|W is conditioned, when lighted, to display its red or stop indication, while the suply of direct current energy from the battery IIIB to the line circuit III is cut off and relay I3WD releases and conditions the signal I 3W, when lighted, to display its yellow or caution indication,

When the train advances from section 26T into section 23T, track relay 23TH releases and interrupts the supply of energy from battery IB over line circuit I to relay 24EI-I so that this relay releases While relay ZI WH remains released. Release of relay ZIIEH conditions the signal 24E to display its red or stop indication.

When the train advances from section 23T into section 22T, relay 22TR releases and interrupts line circuit I to maintain relay 2IIEH released and thus cause signal 24E to continue to display its red or stop indication.

When the train vacates the section next in the West of section MT, the track relay for this section picks up so that energy from a battery, not shown, feeds to the relay 25WH over line circuit VI and this relay picks up and interrupts the circuit of the signal 26E. Likewise, when the train vacates section 24T, relay 24TH picks up and energy is supplied over line circuit VI to relay 23WH and this relay picks up and interrupts the circuit of the signal 24E.

When the train advances into section ZIT, relay 2ITR releases and interrupts line circuits I, III and V. As the line circuit I is interrupted, energy is not supplied from the battery IB to relay MEI-I so that this relay remains released and conditions the signal 24E when lighted to display its red or stop indication. As the line circuit III is interrupted by track relay ZITR, the relay I3WD will remain released after relay 2IWH picks up, which occurs when the train vacates section 22T, and will continue te condition the signal I3W to display its yellow or caution indication as long as section 2 IT is occupied.

As a result of release of relay 2 ITR, the supply of direct current energy from the battery VB to the line circuit V is cut oil' and the relays I3AR and IZAR release and establish the circuits of the signals ISW and IZE, while the relay IIWH releases and conditions the signal IIW when lighted to display its red or stop indication. Furthermore as a result of the release of relay IIWH, circuit VII is interrupted and the supply of current from battery VIIB ceases, whereupon relay 'IWD releases and conditions signal IW to display its yellow or caution indication when lighted.

The relays ISAE and I2AR are connected across resistors which are included in series with the line circuit and which are proportioned to produce suicient voltage drop to operate the relays while not unduly restricting the iiow of alternating current in the line circuit. Similarly the relay I IWH is connected across a resistor RB and the primary winding of the transformer VTT which together provide sufficient drop in the voltage of the direct current in the line circuit to operate the relay.

From the foregoing it will be seen that when the train advances beyond the passing siding M and enters section 2IT, the signal I3W is conditioned to display its caution indication, while signal IIW is caused t display its stop indication when lighted.

When the train advances into section BI3T, the relay BISTR releases and interrupts the line circuit V to maintain relays IZAR and IIWH released and cause signal IIW when lighted to display its stop indication.

When the train vacates section 22T, relay 22TH', picks up and energy from the transformer ITT is supplied over the line circuit I to the relay 2l WH and this relay picks up and interrupts the circuit of the signal 22E, while it also permits energy to be supplied from the battery IIIB to the line circuit III on picking up of relay ZITR which occurs when the train vacates section 2 IT.

When the train advances into section AIST, relay AISTR releases and cuts off the supply of energy from battery VIB to line circuit VI, while it also interrupts line circuit V to maintain relays ISAR, IZAR and IIWH released.

As a result of cutting off the supply of direct current to line circuit VI, the relay I IAR releases to establish the circuit to light signal IIW; relay IAR. releases to light signal IUE; relay BWI-I releases to condition signal 5W when lighted to display its red or stop indication, and to establish the circuit of signal 6E; and relay SWH releases to condition the signal 3W when lighted to display its stop indication, and to establish the circuit of signal 4E.

At this time relay I BED is picked up by energy supplied over line circuit VIII and signal IDE displays its green or clear indication, while relay IZEI-I is picked up by energy from transformer VITT supplied over line circuit VI so that signal I2E displays its green or clear indication and permits the train to advance beyond signal IZE into section IZT.

When the train does advance into section IZT, relay IZTR releases and interrupts line circuit VI so as to cut off the supply of energy to the relay IZEI-I through the associated transformer and rectifier. The relay IZEI-I thereupon releases and conditions the signal IZE to display its red or stop indication.

When the train vacates section 2IT, the track relay ZITR picks up and completes line circuit I and direct current from the battery IB feeds to the relay 24EH and this relay picks up and changes the aspect of signal 24E, when lighted, from red to yellow, While relay ZIIEH establishes line circuit IV so that energy is supplied to relay 26ED which picks up to condition the signal 26E when lighted to display its green or clear indication. In addition, relay NEI-I, when picked up, permits energy to be supplied from line circuit II to relay 2-IED after establishment of line circuit II by picking up of relay 22EH which does not take place until the train vacates section IIT. Accordingly, the signal ZIIE, when lighted, will display its red indication until the train vacates section ZIT, at which time the signal changes from red to yellow, while this indication will continue to be displayed until the train advances far enough to vacate section I IT.

When track relay ZITR picks up, it completes line circuit III and energy is supplied to the relay IBWD so that this relay picks up to condition the signal ISWD to display its green or clear indication.

When the train advances into section IIT, the relay IITR releases and interrupts line circuits V, VI and VII. Line circuits V, VI and VII were already interrupted so release of relay I ITR does not change the condition of these circuits.

When the train advances into section IilT, relay IIJ'IR releases and additionally interrupts line circuits VI and VII and there is no change in the signals at this time.

When the train advances into section 8T, the

relay STR releases and additionally.interrupts the line circuits VI and VII, While .it also interrupts the line circuit VIII so that relay IEIED releases and conditions 'the signal IE to display its yellow or caution indication.

When the train vacates section I2T, the relay I2TR picks up and energy is supplied from the battery VB to energize the relays ISAR, I EAR and IIWI-I in series and these relays pick up so that signals I3W and I2E are extinguished, While signal IIW is conditioned to display its green instead of its red indication.

When the train advances far enough to vacate section IIT, the track relay IIIR picks up and the line circuit V isagain completeand energy is supplied over this line circuit from the transformer VTT to theY relay 22EI-I and this relay picks up to condition the signal 22E when lighted to display its green or clear indication. In addition, picking up of relay 22EI-I completes line circuit II so that energy from the battery IIB picks up the relay MED to .thereby condition the signal 25E when lighted to display its green or clear indication.

When the train advances into section 5T, relay GTR releases and cuts o the supply of energy from the transformer VITT over the line circuit VI to the relay BEI-I and this relay releases and conditions the signal 8E todisplay its red or stop indication, while it also establishes the circuit of the signal "IW,

When the train is present in section 6T, the relay EWI-I is released as the line circuit VI is interrupted by contacts of relay ETR, and as relay EvWI-I is released, the circuit of the signal @E is established. 'At this time, as the track stretch is assumed to be vacant except for the train in section 6T, the relay ISED is picked up by energy supplied over line circuit IV and the signal 6E is conditioned to display its green or clear indication. In addition, as the line Ycircuit VI is interrupted, the relay SWH is released and conditions the signal 3W, when lighted, to display its red or stop indication to thereby prevent a Westbound train leaving the passing siding N while the eastbound train is approaching the siding.

As the train advances from section 5T into sectionv 4T and on past the passing siding N, the signals associated with the passing siding N operate in the manner explained in connection with passing siding M and a detailed description of their operation is not necessary.

Operation of the system on movement of a westbound train through the track stretch For purposes of illustration it will be assumed that the track stretch is vacant and that a westbound train passes `through the track stretch.

When the Westbound train is present in section IT, the track relay ITR is released and interrupts the line circuits I, III and V. As line circuit I is interrupted by track relay ITR, direct current from the battery IB is not supplied over the circuit to relay IIEH, but energy is supplied from the transformer ITT to relay IWH.

As line circuit V is interrupted, relay 2EII is released and establishes the circuit of the signal IW. At this time relay IWH is picked up, as pointed out above, while relayv I WD is picked up by energy supplied from the transformer IITT over the line circuit II. As relays IITD and IWI-I are picked up, signal IW is conditioned to display its green or clear indication.

At this time relay BWI-I is picked up by energy supplied from the battery VIB over the line circuit VI, while the relay EH is released, as explained above, and the signal 3W is conditioned to display its green or clear indication.

In addition, as relay IEH is released line circuit IV is interrupted and relay BED is released and establishes the circuit of the signal 5W so this signal displays its green or clear indication, While the signal 4E when lighted will display its red or stop indication.

When the train advances into section 2T, the track relay ETR releases and cuts off the supply of energy over line circuit I to the relay IWH With the result that signal IW displays its stop indication.

When the train advances into section 3T, the track relay 3TR releases and interrupts line circuit I to maintain relays 4EH and IWH released and thereby maintain signal IW at stop and to also maintain the circuit for lighting the signal 3W.

When the train vacates section I, relay ITR picks up and completes line circuit V so that energy is supplied to relay ZEH and this relay picks up to interrupt the circuit of the signal IW.

When the train advances into section 4T, track relay 4TR releases and interrupts line circuits I, IV and VI. Interruption of line circuit I maintains relay IWH released so that the signal IW when lighted will display its stop indication, While interruption of line circuit IV maintains relay ISED released to maintain the circuit of the signal 5W.

Interruption of the line circuit VI by the track relay ETR cuts off the supply of alternating current from the transformer VITT to the line circuit VI and relay SEI-I releases and establishes the circuit of signal TW. At this time relay 1WD is picked up by energy supplied over the line circuit VII and the signal 'IW is conditioned to display its green or clear indication.

In addition, on release of relay EIEH line circuit VIII is interrupted and relay ISED releases and conditions the signal ISE when lighted to display its yellow or caution indication.

On release of relay ITR and interruption of the supply of alternating current to the line circuit VI relay IZEH releases and conditions signal IEE when lighted to display its red or stop indication.

Interruption of the line circuit VI by the track relay IITR cuts off the supply of direct current energy over the line circuit VI to the relay 3WH and this relay releases to condition the signal 3W to display its stop indication. Release of relay GTR does not affect the supply of energy from the battery VIB to the relays IIAR, IUAR and SWH over the line circuit VI and these relays are energized in series. Accordingly, the relay EWI-I remains picked up and conditions the signal 5W to display its green or clear indication.

When the train advances into section 6T, relay STR releases and interrupts the line circuit VI so as to interrupt the series connection of the relays I IAR, IiiAR and 5WI-I and these relays thereupon release. Release of relay IIAR establishes the circuit of the signal IIW, While release of relay I UAR establishes the circuit of the signal ISE, and release of relay 5WH conditions signal 5W to display its red or stop indication.

When the train vacates section 2T, track relay ZTR picks up, While When the train vacates section 3T, the track relay STR picks up and energy is sup-plied from battery IB over line circuit I to relay 4EH. As a result, relay 4EH picks up and interrupts the circuit of signal 3W.

When the train vacates Section 4T, the track relay 4TR picks up and completes line circuits I and IV. As a result, energy from the transformer ITT is supplied to the relay IWH over the line circuit I and this relay picks up to interrupt the circuit of the signal 2E and to condition the signal IW when lighted to display its green or its yellow indication. As the line circuit IV is complete, energy from the transformer IVTT is supplied to the relay BED and this relay picks up and interrupts the circuit of the signal 5W.

When the train advances into section 8T, relay STR releases and interrupts line circuits VI, VII and VIII. As a result of interruption of line circuit VII, relay IWD releases and causes the signal 'IW to display its caution indication, while interruption of line circuit VIII maintains relay IIIED released after the train vacates section 6T and relay 8EI-I picks up.

When the train advances into section I IIT, relay IEITR releases and interrupts line circuits VI and VII so that relay 'IWD remains released and relays I IAR, IAR and EWH also remain released.

When the train vacates section 6T, relay STR picks up so that energy from the transformer VITT feeds to the relay SEH over the line circuit VI and relay EEH picks up and interrupts the circuit of the signal 1W.

When the train vacates section 8T, the relay TR picks up and completes line circuit VIII so that relay IIIED picks up and conditions signal IEEE to display its green or clear indication.

When the train advances into section IIT, track relay I ITR releases and interrupts line circuits V, VI and VII. Interruption of line circuit V cuts off the supply of energy from the transformer VTT to relay ZZEII and this relay thereupon releases and conditions signal 22E' when lighted to display its red or stop indication.

At this time relay I IAR is released as line circuit VI is interrupted, while relay I IWH is picked up by energy supplied from battery VB over line circuit V. Accordingly, the signal IIW displays its green or clear indication.

When the train advances into section I2T, track relay IZTR releases and interrupts line circuits V and VI. Interruption of line circuit V by the relay I2TR interrupts the circuit for energizing I SAR, IZAR and I IWH in series from the battery VB and these relays thereupon release. Release of relay IIWH causes signal IIW to display its red or stop indication, and interrupts circuits VII to continue the deenergization of relay 1WD,

while release of relays IZAR and IBAR establishes the circuits of the signals IZE and I3W. At this time relay IZEI-I is released las line circuit VI is interrupted and accordingly signal IZE displays its stop indication. In addition, at this time relay ISWD is picked up by energy supplied over line.

circuit III so that signal I3W displays its green or clear indication.

When the train vacates sections IDT and IIT, the track relays IIiTR, and IITRI pick up. However, relay IIWH is released and maintains circuit VII deenergized so that energy is not supplied to relay 'IWD and signal IW when lighted displays its .yellow or caution indication.

When the train advances into section AI 3T, the track relay AISTR releases and additionally interrupts the line circuits V and VI, while when the train advances into section BIST, the track relay BI3'IR. releases and additionally interrupts line circuit V.

When the train -advances into section ZIT, relay ZITR releases and interrupts line circuits I, III and V. On this interruption of the line circuit I thesupply of energy from the battery IB to the relay MEI-I is cut 01T, but the supply of energyfrom the transformer ITT to the relay 2 IWH is maintained. At this time relay 2 IWD is picked up by energy supplied from transformer II'IT over line circuit II, while relay ZZEH is released as line circuit V is interrupted, and accordingly signal 2IW is lighted and displays its green or clear indication.

As relay ZIIEH is released, the circuit of signal 23W is established, While this signal displays its green indication as relay MWI-I is picked up by energy supplied over line circuit VI.

, As line circuit III is interrupted, relay I3WD is released, and as line circuit V is interrupted, relay ISAR is released so that signal I3W is lighted and displays its yellow or caution indication.

When the train vacates section I2T, relay ITR picks up and energy from the transformer VI'IT 1s supplied over the line circuit VI to the relay IZEI-I and this relay picks up to condtion the signal I2E to display its green or clear indication.

Picking up oi' track relay IZTR does not permit the supply of energy from the battery VIB to the line circuit VI and accordingly relays 3WH and 5WI-I remain released. As relay SWH is released, the signal 3W when `lighted will display its red or stop, indication to warn a second or following westbound train of the presence of the first train in the track stretch. Likewise, as relay 5WH is released, the signal 5W when lighted will display its red or stop indication.

When the train vacates section AIT, track relay AI3IR picks up and completes line circuit VI so that energy-from the .battery VIB is supplied over the line circuit VI to the relays I IAR, IIIAR, BWI-I and SWH. As relays SW1-I and E'WH are picked up, the signals 5W and 3W when lighted display their green or clear indications. As relays l IAR and IliAR are picked up, the signals IIW and IUE are dark.

When the train vacates section BI3'I", the relay BIiTR picks up, but line circuit V continues to be interrupted by track relay 2ITR and relay IIWI-I remains released and conditions the signal IIW when lighted to display its red or stop indication aslong assection ZIT is occupied.

Line circuit VII continues to be interrupted by relay IIWH and relay 'IWD remains released and conditions signal IW when lighted to display its yellow or caution indication as long as circuit V is interrupted.

As the train proceeds through the track stretch past the passing siding M, the signals associated with this passing siding operate as described in connection with passing siding N and a detailed explanation of their operation is not necessary.

Operation of system in response to movement of trains through the track stretch, in opposite directions Warning of the approach of each other so that they can stop before colliding head-on.

When an eastbound train advances beyond passing siding M into section 2IT, relay 2ITR interrupts line Circuit. V so, that Aenergy isnot su'ppiied over this circuit to the relays IBAR, [ZAR and IIWHV. As relay HWI-I is released, the' siguen uw; wheniightei displays its stop indication` to prevent a westbound train from proceeding f beyond this point. Furthermore, with the release of relay I I WHk line vcircuit VII is interrupted to`I cause the release of relay 1WD. As `relay 'IWD'is released, the signal 'IW when lig'hteddisplays its yellow or caution indication.

The'flight'ing' of 'signal IIW is controlled by relay HAR whichV is energized from line circuit VI and becomes released when a westbound train enters section 6T, and the lighting of signal 'IW is controlled by relay'EH which is energized by transformer VITT over circuit VI and becomes released when a westboundtrain enters section 4T. Accordingly, when an eastbound train is present in section 2 IT, a westbound train is rst warned by signal IW and is prevented from proceeding beyond signal IIW. The westbound train having approached signal I IW with caution will be able to stop before passing that signal, and therefore will not collide with the eastbound train.

As soon as a westbound train advances beyond passing siding N and enters section 4T, line circuit VI is interrupted so that energy from the transformer VITT is not supplied to the relay I2EI-I and this relay releases and causes the signal IZE to display its stop indication. Accordingly, the eastbound train which was assumed to be present in section 2IT will not advance beyond signal I2-E. Since the westbound train is prevented from advancing beyond signal IIW, the two trains are separated by section I2T and are prevented from colliding.

When an eastbound train advances into section AIST; the track relay AI3TR- interrupts the line circuit VI -so that energy is not supplied from the battery VIB over the line circuit V'I'to the relays EWH and SVV-H and these relays are released to condition the signals- 5W- and 3W to display stop indications. The release of relay 3WI-I interrupts line circuit I-Ivwhich Yreleases relay IWDV to condition that signal to display its yellow or cautionA indication when lighted. AsV the signal 3W displays a stop indication andv signal IW- ,displays a caution indication, a westbound train is prevented from proceeding beyond the passing siding NV and the eastboundtrain can continue until it reaches passingl siding- N.

If a westbound train is present in section V3T waiting for..theeastbound train, relaynllEHwill be released and will interrupt line circuit IV so that relay BED is released and signalGE displays a caution indicationto cause V.the eastbound train to approach the `passing sidingl slowly.

In similar,k mannerthe `equipmentoperates to preventa head-,on collision betweentrains if'la westbound trainadvancesbeyond a passing siding before an eastbound train does.

If, for example, a westbound trainA enters section 4T, line circuit VI is interrupted sov that energy from the transformer VITT is not supplied tothe relays SEH and IZEH-'and these relays release ,s and Acause signals Ei-and `I2E when lighted to. display redvor stop indications and thereby preventlmovement of eastbound trains beyond these points.

If an eastbound trainnow enters section ZIT, line circuit V is interrupted and relay IIWH releases and signal I IW is conditioned to display its stop indication. Relay II WH when released interruptsgline circuit VIIand releases relay 1WD and signal 'IW is conditioned to display its caution indication. Accordingly, a westbound train approaches signal IIW with caution and would not advance beyond signal IIW, while an eastbound train would vnot advance beyond signal I 2E and the two trains would be separated by block I2T.

If before an eastbound train enters section 23T the westbound train advances into section IIT, the track relay IITR will interrupt the line circuit V and prevent the supply of energy from the transformer VTT to the relay 22EH. Relay 22EH when released interrupts circuit II so that direct current energy ceases to iiow from battery IIB and relay 24ED releases. As relay 22EH is released, signal 22E is conditioned to display its stop indication and since relay 24ED is released, signal 24 is conditioned to display its caution indication. Accordingly, an eastbound train will approach signal 22E' with caution and will not proceed beyond the passing siding M.

From the foregoing it will be seen that the system provided by this invention provides improved means for controlling the signals which govern movement of traiiic in both directions over a track stretch, and that the system functions to provide protection both for trains moving in the same direction and for trains moving in opposite directions. In addition, it will be seen that several of the line circuits are arranged so that alternating current is supplied to one end of the line conductors, and direct current to the other end of the line conductors so that these line circuits serve two functions, thereby reducing the number of line circuits required.

The system provided by this invention is adapted for use where semaphore signals are employed and. Fig. 2 is a diagram showing this modification of the invention.

Construction and operation of modification shown in Fig. 2

Fig. 2 is a fragmentary view similar to Fig. l and showing the portion of the track stretch between the passing siding M and the signal IIW. This track stretch is shown equipped with semaphore signals which may be of any wellknown construction. One form of signal which may be employed is shown in United States Patent No. 1,307,741 issued June 24, 1919, to Lloyd V. Lewis. Each of these signals has a semaphore arm which is movable from a horizontal or stop position to a position in which it provides a proceed indication. This may be a 45 position` in which it indicates caution, or a position in which it indicates clear, while some or all of the signals may be arranged to provide both indications.

Each of the signalsis provided with an electric motor for moving the semaphore arm from its stop to its proceed positions, while each of the signals also is provided with a holding coil K which when energized establishes a driving connection between the motor and the semaphore arm so that the motor will'move thearm. In addition, the holding coils when energized serve to hold the semaphore armsv in the positions to which theyhave been moved.

The signals each alsoV have a lamp which is mounted so that light from the lampl is projected through roundels carriedv by the sernaphore arm. These roundels have diierent colored lensesmounted therein and are positioned so that when the semaphore arm is `in its horizontal or stop position, a red lens is located in,

front of the lamp; when the semaphore arms is in its 45 position, a yellow lens is located in front of the lamp; while when the semaphore arm is in its 90 or vertical position, a green lens is located in front of the lamp. The circuits of the lamps of the signals are approach controlled so that the lamps are normally dark and become lighted on the approach of a train.

The signals employed in the modiiication shown in Fig. 2 are provided with holding coils having two windings, one of which is energized in series with the motor for moving the semaphore arm, while the other Winding is energized from the line circuit over which energy is supplied to the relay which controls the signal.

The equipment is shown in the condition which it assumes when the track stretch is vacant. At this time the track relays are picked up and the line circuit V is complete so that energy from the battery VB is supplied over the line circuit to energize the relays I3AR and IZAR and the winding 3| of the holding coil K of signal IIW in series.

As the relays I3AR and |3AR are picked up, the circuits of the signal lamps controlled thereby are interrupted, while as Winding 3| of holding coil K of signal I IW is energized, the semaphore arm of this signal is held in its 90 or vertical position to provide the clear indication. As the signal arm is in its 90 position, the signal controlled contacts are open and interrupt the supply of energy from the line circuit to the winding of relay I IWH. The signal controlled contacts are arranged so as to be closed in all positions of the semaphore arm except its vertical or 90 position.

As the relay IIWH is released, its contacts interrupt the circuit for supplying energy from a battery to the motor J which moves the semaphore arm.

In like manner, energy from the transformer VTT is supplied over the line circuit and through the transformer and rectiiier associated with signal 22E to the winding 3| of the holding coil K of this signal. As this holding coil winding is energized, the semaphore arm of this signal is held in its 90 or vertical position to provide the clear indication. As the signal armis in its 90 position, the signal controlled contacts are open and energy from the line circuit is not supplied to the relay 22EH so that this relay is released and interrupts the circuit of the switch motor J..

If an eastbound train enters section 2 |T,track relay 2'ITR releases and interrupts line circuit V so that the supply of energy from the transformer VTT to the winding 3| of holding coil K is cut oif Yand the holding coil releases the semaphore arm. Accordingly, the semaphore arm drops to its horizontal or stop position, thereby closing the signal controlled contacts. However, at this time no energy is supplied to the relay ZZEH as the track relay 2 ITR is released and relay 22EH remains released and interrupts the circuit of the signal motor J.

Release of track relay 2ITR. also cuts oi the supplyof energy from the battery VB to the line circuit V and thus to the Winding 3| of the holding coil K of signal IIWH and this coil releases the semaphore arm of the signal so that this arm moves to its horizontal position to provide the stop indication.

When the train advances far enough to vacate section I2T, the relay IZTR picks up and energy from the battery VB is supplied to the relay I IWH and to winding 3| of holding coil K in multiple.

The circuit for supplying energy to the relay IIWH is complete as the semaphore arm of the signal IIW is in its horizontal or stop position and the signal controlled contacts are closed. A

On the supply of energy to the winding 3| of the holding coil K the magnet operates in the manner well-known in the art to establish driving connection between the motor and the semaphore arm so that the motor will move the semaphore arm to the vertical position. When energy is supplied to the relay IIWH, its contacts pick up and establish the circuit to supply energy from a battery to the motor J and winding 32 of the holding coil K in series. On the supply of energy to the motor J it operates in the customary manner to move the semaphore arm from its horizontal to its vertical or clear position.

At this time the windings 3| and 32 of holding coil K are both energized and these windings are arranged so that they assist each other to maintain the driving connection between the motor and the semaphore arm. When the arm is being moved by the motor, there is a possibility that the driving connection between the motor and the arm may be disrupted unless it is iirmly established. The arrangement provided by this invention is such that both windings of the holding coil are energized while the arm is being driven by the motor so that the maximum force is exerted to maintain the driving connection between the motor and the signal arm to thereby insure that this connection will be maintained.

When the signal arm reaches its vertical or 90 position, the signal controlled contacts open and interrupt the supply of energy to the relay IIWH so that the contacts of this relay release and interrupt the supply of energy to the motor J and to the winding 32 of the holding coil K. The winding 3| of the holding coil K continues to be energized from the line circuit V and maintains the semaphore arm in its vertical or clear position.

When the train advances far enough to vacate section IIT, the track relay IITR picks up and energy from the transformer VTT is supplied over the line circuit V through the transformer and rectier associated with the line circuit to the relay 22EH and to the winding 3| of the holding coil K associated with signal 22E.

On the `supply of energy to the holding coil K it establishes driving connection between the motor J and the signal arm, while the relay 22EI-I when picked up establishes the circuit to supply energy to the motor J and to the Winding 32 of the holding coil K so that the motor moves the semaphore arm to its clear position.

When the semaphore arm reaches its 90 or clear position, the signal controlled contacts open and interrupt the supply of energy to the relay 22EI-I, and this relay releases and cuts off the supply of energy to the motor J and the winding 32 of the holding coil K. Thereafter the signal arm is held in its vertical position by the windingr 3| of the holding coil which continues to be energized over the line circuit V.

The signals operate in substantially the same manner on movement of a westbound train through the track stretch.

In addition, it is contemplated that the system shown in Fig. 2 will include other line circuits and associated apparatus as shown in Fig. 1 to control signals 2|W, |3W and IZE, and to also control lighting of the lamps, not shown, assoelated with signals 22E and I ITR. In order to simplify the disclosure these have been omitted from Fig. 2.

Construction of modification shown in Fig. 3 of the drawings The lnodication shown in Fig. 3 of the drawings is similar to that shown in Fig. 1, but provides means to provide a larger number of signal indications than the system shown in Fig. 1, while it requires fewer line wires than the system shown in Fig. 1.

The modication shown in Fig. 3 of the drawings, like that shown in Fig. l, employs direct current in a line circuit to control the signals for one direction of traic, and employs alternating current in the same line circuit to control the signals for the other direction of traffic. The system shown in Fig. 3 diiers from that shown in Fig. l in that it employs the two polarities of direct current to provide two proceed indications, while it employs coded and steady alternating current energy to also provide two proceed indi cations.

Referring to Fig. 3 of the drawings, there is shown therein a stretch of single track railroad having track rails I and 2 over which trafiic moves in both directions. The rails of the track are divided by insulated joints into the customary track sections, while passing sidings are provided at appropriate intervals to permit traiiic to be diverted from the main track under the customary control of switches, not shown. Two such passing sidings are shown and are designated P and Q..

As in the system shown in Fig. 1, it will be assumed that the right-hand end of the track stretch is east and that the left-hand end is west. Likewisey in the system shown in Fig. 3 the signals governing westbound traino are identied by odd numbers, while the signals governing eastbound trailic are identified by even numbers. The signals starting at the east end of passing siding Q are numbered in a series starting with lW, while the signals starting at the east end of passing siding P are numbered in a series starting with ZIW. The reference characters for the westbound signals include the suiix W, while the reference characters for the eastbound signals include the sufiix E. The track sections are numbered in a series corresponding to that of the signals.

The signals are shown as being of the color light type, while each of the signals has associated therewith a local source of direct current,

the terminals of which are designated (-I-) and While color light signals are shown, the invention is not limited to the use of signals of this type and any desired form of signals may be employed.

Each of the track sections is provided with a track circuit including a track battery connected across the section rails at one end of the section, and a track relay, designated TR with a suitable prex, connected across the section rails at the other end of the section.

This system, like that shown in Fig. 1, employs line circuits for controlling the signals, while these line circuits are controlled by contacts of the track relays.

In the system shown there is a line circuit X which is substantially coextensive with the passing siding Q, while a line circuit XI extends westward from the passing siding Q and overlaps a line circuit XII which extends eastward from the adjacent passing siding P to the west. Similarly there is a line circuit XX which is substantially coextensive with the passing siding P, while a line circuit XXI extends westward from the passing siding P.

Each of the line circuits has a battery at one end thereof, and a transformer at the other end thereof. In addition, each circuit has a reactor RA included therein to limit the flow of alternating current in the battery and a resistance RB to substantially limit the flow of direct current in the transformer secondary winding. Each of the line circuits has a direct current relay energized by direct current supplied over the line circuit and also has a direct current relay energized from the line circuit through a transformer and a rectifier so that the relay is energized only when alternating currentenergy is supplied over the line circuit.

The equipment is shown in the condition which it assumes when the track stretch is vacant. At this time the track relays are picked up and the various line circuits are all complete.

As the line circuit X is complete, energy from the battery XB is supplied over the line circuit to the relay IWR, so that the neutral contacts of this relay are picked up. As the neutral contacts of relay SWR are picked up, the polarity of the energy supplied from the battery XB to the relay IWR is such that the polar contacts of the relay EWR occupy their left-hand or normal positions as shown. Accordingly, the green or clear lamp G of signal IW is lighted by energy supplied over the circuit which is traced from one terminal of a local source of current through front contact I and normal polar contact IUI of relay IWR and lamp G to the other terminal.

In addition, at this time a circuit is established to supply coded alternating current energy to line circuit IX which extends to the east of passing siding Q. The coded energy is provided by a code transmitter CT which, like the other code transmitters employed in this system, has a contact ISB which is continuously operated by a motor or other means at a rate effective to provide 180 energy impulses a minute separated by periods of equal length during which no energy is supplied. While the system is described as employing energy of 180 code frequency, it should be understood that any other code frequency may be employed.

The circuit for supplying energy to the line circuit IX' is traced from terminal BX of a source of alternating current through contact I8!) of code transmitter CT, normal polar Contact |02 and neutral front contact HB3 of relay IWR, and the primary winding of transformer IXTT toeterminal CX. The secondary winding of the transformer IXTT is included in series with the line circuit IX,

At this time relay 2ER is energized by direct current supplied over line circuit IX and its contacts establish a circuit to light the green or clear lamp of signal 2E. This circuit is traced from one terminal of a source of current through front contact H15, normal polar contact |66 of relay 2ER, and lamp G of signal 2E to the other terminal.

In addition, relay 2ER establishes a circuit to supply coded alternating current energy to line circuit X. This circuit is traced from terminal BX through front contact ISB of relay 2ER, contact E89 of code transmitter CT and primary winding of transformer XTT to terminal CX. The secondary winding. of the transformer is included in series with the line circuit X, and as the contacts of track relays TR, ZTR and 3TH. are picked up, coded energy is supplied over the line circuit X to relay 4ER through the associated transformer and rectifier.

As a result of code following operation of the relay 4ER., energy is supplied to relay 4H during the picked-up periods of the contacts of relay AER. The relay 4H is of the type which is slow to release so its contacts remain picked up between the supply of impulses of energy thereto. As contact I of relay 4H is picked up, the circuit of the primary winding of decoding transformer 4DT isl established so that as long as relay 4ER follows coded energy current is'supplied through the decoding transformer 4DT to the relay 4J and the contacts of this relay are picked up. As relays 4H and 4J are both picked up, a circuit is established to light the green or clear lamp of signal 4E. This circuit includes front contact of relay 4H and front contact H2 of relay 4J.

In addition, at this time coded alternating current energy is supplied to transformer XITT over a circuit which is traced from terminal BX through contact |80 of a code transmitter CT, front contact ||l| of relay 4J, front contact H5 of relay 4H and primary winding of transformer XITT to terminal CX.

In like manner, the relays 5WR, BER and 24ER respond to coded alternating current supplied over the line circuits XII, XI and'XX so that the signals 5W, 6E and 24E are conditioned to display green or clear indications, while relay 24ER causes coded alternating current to be supplied to line circuit XXI. Similarly, the relays SWR, 2|WR, 22ER and 23WR are energized by direct current energy supplied over the line circuits XI, XII, XX and XXI and condition the signals 3W, 2|W, 22E and 23W to display green or clear indications, While relay 22ER establishes the circuit to supply coded alternating current to the line circuit XII.

Operation of equipment on movement of cm eastbound train through the track stretch When an eastbound train enters section 24T, the track relay MTR releases and cuts off the supply of direct current to line circuit XX, while it also interrupts line circuit XXI so that relay 23WR. releases. causes signal 23W to display its red or stop indication to prevent a westbound train from advancing beyond the passing siding P. The circuit of the red lamp of signal 23W includes back contact |20 of relay 23WR.

Release of track relay 24TH does not affect the supply of energy from transformer XXTT over line circuit XX to relay MER, but it cuts off the supply of energy from battery XXB to relay ZIWR. Release of relay 2|WR interrupts the circuit of the green lamp G and establishes the circuit of the red lamp R of signal 2 IW. The circuit of the lamp R of signal 2|W includes back contact |2| `of relay 2 IWR.

Deenergization of relay ZIWR also interrupts the circuit for supplying coded energy to the line circuit XII and establishes a circuit to supply steady uncoded alternating current to this circuit. This circuit includes back contact |22 of relay 2|WR.

As a result of the change in the alternating current energy supplied to line circuit XII from coded to steady, the relay EWR ceases to follow code so that relay 5J releases, While the contacts of relay EWR remain picked up so that energy Deenergization of relay 23WR' is supplied to relay 5H and this relay remains energized. On release of relay 5J while relay 5H is picked up, the green lamp G of signal 5W is extinguished and the-yellow lamp Y is lighted. The circuit of the lamp Y includes front contact |24 of relay 5H and back contact |25 of relay 5J It will be seen, therefore, that when a train is present in section 24T, the signals 23W and 2|W are both conditioned to display red or stop indications, while the signal 5W is conditioned to display its yellow or caution indication. Accordingly, a westbound train will receive a restrictive indication before reaching the passing siding and will receive a stop indication at the east end of the siding P. rIhis insures that the westbound train will have ample warning of the approach of an eastbound train.

When the eastbound train advances into section 23T, relay 23TH releases and additionally cuts off the supply of energy from the battery XXB to line circuit XX, while it also cuts off the supply of energy from the transformer XXTT to the relay MER so that this relay ceases to respond to coded energy. On deenergization of relay MER relays 24H and 24J release and interrupt the circuit of the green lamp G of signal 24E and establish the circuit of the red lamp R of this signal. The circuit of the red lamp includes back contact |26 of relay 24H. In addition, as a result of release of relay 24H, contact |21 interrupts the circuit of the primary Winding of decoding transformer 24DT to thereby prevent consumption of energy by this transformer at this time.

As aresu1t of the* release of the relays 24H and MJ, the circuit fior supplying coded energy to the transformer XXITT is interrupted and a circuit including back contact |28 of relay 24H is established to supply steady uncoded energy to this transformer. On this change in the energy supplied to line circuit XXT the eastbound signal next in the rear of signal 24E will be conditioned to display a yellow or caution indication when the train Vacates section 24T.

When the train advances into section 22T, track relay ZZTR releases and additionally interrupts line circuit XX, While there is no other change in the equipment at this time.

When the train vacates section 24T, track relay 24TR picks up and permits energy to be supplied over line cir-cuit XXI to relay 23WR and this relay establishes the circuit ofthe green lamp Gr of signal 23W. This circuit includes front Contact |20, normal polar contact |39 and lamp G of signal 23W.

When the train vacates section 23T, track relay 23'I'R picks up, but there is no other change in the equipment at this time.

When the train enters section 2|T, 2|TR releases and interrupts the line circuits XX and XII. In interruption of line circuit XII relays 22ER and EWR release. Release of relay NER cuts off the supply of coded alternating current' energy to line circuit XX and establishes a circuit to supply steady energy to this circuit, While it also conditions signal 22E to display its red or stop indication. The circuit of the red lamp R of signal 22E includes back contact |3| of relay J2EE, while the circuit for supplying steady alternating current energy to the line circuit XX includes back contact |32 of relay 22ER. At this time as section 2|T is occupied and track relay 2|TR is released, energy. is not supplied from the transformer XXTT to the line circuit XX so relay 24ER remains released and the signal 24E continues to display its stop indication,

As a result of interruption of the supply of energy to relay SWR, the relay 5H releases and interrupts the circuit of the yellow lamp Y of signal 5W and establish the circuit of the red lamp R of this signal. The circuit of the red lamp includes back contact |2 or relay 5H. On release of relay 5H its contact |23 interrupts the circuit of the primary winding of transformer 5DT. l In addition, on release of relay 5H contacts i3d and |35 of this relay reverse the polarity of the energy supplied from the battery XIB over the line circuit XI to relay 3WR so that the polar Contact I 3l' of relay 3WR is shifted from its normal to its reverse position to thereby interrupt the circuit of the green lamp G of signal EW and establish the circuit of the yellow lamp Y. The circuit of the yellow lamp Y includes front neutral contact |33 and reverse polar Contact |37 of relay SWR.

It will be seen, therefore, that as soon as an eastbound train advances beyond the passing siding P and enters section EIT, line circuit XII is interrupted so that relay SWR is deenergized and conditions the signal 5W to display its red or stop indication, while the polarity or the energy supplied to line circuit XI is changed so that relay EWR conditions signal 3W to display its yellow or Caution indication. Accordingly, a westbound train will receive a caution indication from signal 3W and would be prevented from proceeding beyond signal 5W so that it will not collide with the eastbound train.

When the eastbound train advances into section ITI, the track relay ITR releases and inu terrupts the line circuits XII and XI. Interrupu tion of line circuit XII maintains relay WR deenergized to thereby cause signal 5W to continue to display its stop indication, while interruption of line XI cuts ofi the supply of energy to relay SWR so that the neutral contact |33 of this relay releases and interrupts the circuit of the yellow lamp Y of signal BWR and establishes the circuit of the red lamp R of this signal.

In addition, on release of the neutral contacts of relay 3WR contacts I and IGI change the polarity of the energy supplied from battery XB to line circuit X so that the polar contacts of v relay IWR are shifted from their normal to their reverse positions. On this movement of contact of relay IWR, the green lamp G of signal IW is extinguished and the yellow lamp Y of this signal is lighted. On movement oi contact |32 to its reverse position the supply of coded energy to the line circuit IX is cut off and steady alternating current energy is supplied to this circuit so that the westbound signal next in the east of signal IW is caused to display a yellow instead of a green induction.

As a result of signal IW and the signal next to the east displaying caution indications, a westbound train approaching siding Q would receive ample warning of a meet with the eastbound train to enable the westbound train to stop at signal IW and enter siding Q.

When the train vacates section 22T, relay 22TH, picks up so that energy from the battery XXB is supplied to the relay ZIWR, and the neutral contacts of this relay pick up, while the polar contacts of the relay occupy their normal position. As a result ci this energization of the relay ZIWR, Contact |2| is picked up and contact |42 occupies its normal position so that space42 the circuit of the green lamp G of signal 2|W is complete.

In addition, as contact |22 of relay 2|WR is picked up and contact |43 occupies its normal position, the circuit for supplying energy of code frequency to the transformer XIITT is complete. However, at this time the line circuit XII is interrupted by track relays 2|'IR and ITR so that energy is not supplied over the line circuit to relay BWR.

When the train advances into section 6T, track relay GTR releases and additionally interrupts line circuit XII, while it interrupts line circuit XI in such manner as to cut oir the supply of energy over this line circuit from the transformer XITT to the relay SER. Relay GER, therefore, ceases to follow code and relays 6H and 6J release and condition signal 6E to display its red or stop indication. The circuit of the red lamp of signal 6E includes back contact |45 oi relay 6H, while Contact Ili'I of relay 6H cuts off the supply of energy to the decoding transformer EDT. In addition, on release of relay 6H contacts |48 and |49 of this relay establish connections to supply energy of reverse polarity instead of normal polarity from the battery XIIB to the line circuit XII.

When the rear of the train vacates section ZIT, track relay ZITR picks up and completes line circuit XX so that energy from the transformer XXTT is supplied to the relay MER. At this time neutral contact |32 of relay 22ER is released as line circuit XII is interrupted. Accordingly, steady energy is supplied to the transformer XXTT and is supplied therefrom to relay ZIIER so that the contacts of this relay pick up and establish the circuit of relay 24H. Energy is not supplied through the decoding transformer MDT to relay 25J so that a circuit is established including front contact |26 of relay 24H and back contact |58 of relay 24J to light the yellow lamp Y of signal 24E.

At this time steady energy continues to be supplied to the transformer XXITT over a circuit which includes back contact |5| of relay 24J and front contact |28 of relay 24H, so that the eastbound signal next in the west of signal 24E is conditioned to display a yellow or caution indication.

When the train advances into section 5T, the track relay ETR releases and additionally interrupts line circuits XII and XI, but there is no change in the condition ol the signals at this time.

When the rear oi the train vaoates section 1T, track relay 'ITR picks up, but there is no change in the signals as relay 6TH, interrupts line circuits XII and XI.

'When the Vtrain advances into section 4T, the track relay ITR releases and interrupts line circuit X so that energy from the `battery XB is no longer supplied to the relay IWR. Accordingly, the neutral contacts of relay IWR release and contact Ill establishes the Vcircuit of the red or stop lamp R of signal iW, while contact |03 establishes the circuit to supply steady energy to the transformer IX'IT with the result that the next westbound signal east of signal IW remains conditioned to display its caution indication.

At this time relay GER continues to receive coded energy over the line circuit X from the transformer XIT so that signad 4E continues `to display its green or clear indication.

When the rear of the train vacates section 6T,

track relay GTR picks up 'so that coded energy from the transformer XIITT is supplied over the line circuit XII to relay SWR. Accordingly, relays H and 5J pick up and cause the signal 5W to display its green or clear indication.

When the train advances into section 3T, the track relay STR releases and cuts 01T the supply of energy to the relay IIER and the relays 4H and 4J release and condition the signal 4E to display its red or stop indication. Release of these relays also cuts off the supply of coded energy to the transformer XITT and effects the supply of steady energy thereto.

When the rear of the train vacates section 5T, track relay 5TR picks up and completes line circuit XII so that energy from the battery XIIB feeds to the relay 22ER. At this time relay ER is released as line circuit XI is interrupted by track relay #ITR so that relay 6H is released and its contacts |43 and |49 reverse the polarity of the energy supplied from the battery XIIB to line circuit XII. Accordingly, the polar contact |53 of relay 22ER is shifted to its reverse position to condition the signal 22E to display its yellow or caution indication. The circuit of the yellow lamp Y of signal 22E includes front contact |3| and reverse polar contact |53 of relay ZZER.

On picking up of the neutral contacts of relay ZZER contact |32 interrupts the supply of steady energy to the transformer YXTT and effects the supply of coded energy thereto so that coded energy is supplied to the relay MER and this relay follows code so that energy is supplied through the transformer MDT to relay MJ. On picking up of the contacts of the relay 2M the aspect of signal 24E is changed from yellow or caution to green or clear, while a circuit including front contact |5| of relay 24J and front contact |28 of relay 24H is established to supply coded energy to the transformer XXITT and thus to the line circuit XXI so that the eastbound signal next in the west of signal 24E is conditioned to display its clear indication.

When the train advances into section 2T, the track relay ZTR releases and interrupts the line circuit X, but there is no change in the condition of the signals as this line circuit is already interrupted by track relay STR.

When the train vacates section 4T, track relay ATR picks up so that energy from the battery XIB'is supplied over the line circuit XI to the relay 3WR. At this time relay 5H is picked up so that energy of normal relative polarity is supplied to the relay 3WR and this relay conditions signal 3W to display its green or clear indication.

As the train continues through the track stretch past siding Q, the signals associated with this siding operate in the same manner as the signals associated with siding P and their operation will not be traced in detail.

Operation of system on movement of a westbound train through the track stretch For purposes of illustration it Will be assumed that the track stretch is vacant and that a westbound train passes through the track stretch.

As the track stretch is vacant, the signals will be conditioned to display green or clear indications as explained in detail above.

When the westbound train enters section IT, the track relay ITR releases and interrupts line circuits IX and X. As line circuit IX is interrupted, relay 2ER is released and conditions CII signal 2E t0 display its red or stop indication, while interruption of line circuit X by track relay ITR cuts off the supply of energy from transformer XTT over line circuit X to relay 4ER. Relay 4ER, therefore, releases and relays 4H and 4J release and condition signal 4E to display its red or stop indication, while as con tact ||5 of relay 4H is released, coded energy is no longer supplied to the transformer XITT and steady energy is supplied thereto.

On this change in the energy supplied to line circuit XI relay SER ceases to follow code and energy is not supplied through the transformer 6DT to the relay 6J. However, relay SER is steadily energized so that relay 6H is picked up and causes energy of normal relative polarity to be supplied from battery XIIB to line circuit XII, and to establish the circuit of the yellow lamp Y of signal 6E. This circuit includes front contact |45 of relay 6H and back contact |46 of relay 6J.

As energy of normal relative polarity is supplied over the line circuit XII to relay ZEER, this relay conditions signal 22E to display its green or clear indication, while neutral contact |32 of this relay is picked up and establishes the circuit for supplying coded energy to the transformer X'XTT.

From the foregoing it will be seen that when a train is present in section IT, signal 4E dise plays a stop indication, while signal 8E displays` its yellow or caution indication. Accordingly, an eastbound train will receive ample warning of the approach of a westbound train and will be able to stop before colliding with the westbound train.

When the westbound train advances into section 2T, track relay 2TR releases and cuts off the supply of energy over line circuit X to relay IWR and relay IWR releases and conditions signal IW to display its stop indication, while contact I3 releases and effects the supply of steady energy to transformer IXTT.

When the train advances into section 3T, the track relay 3TR releases and additionally interrupts line circuit X, but there is no change in the signals at this time.

When the train vacates section iT, track relay ITR picks up and energy is supplied over line circuit IX to relay 2ER and this relay causes signal 2E to display its green or clear indication, while contact ||l8 of this relay also establishes the circuit to supply coded energy to the trans former XTT.

When the train advances into section 4T, track relay 4TH releases and additionally interrupts line circuit X, while it also cuts off the supply of energy from battery XIB over line circuit XI to relay SWR and from transformer XITT to line circuit XI.

AsV a result of deenergization of relay SWR, signal 3W displays its stop indication, while on cutting off of the supply of energy from the transformer XITT to line circuit XI relay BER releases and relay 6H also releases so that signal EE displays its stop indication. In addition, on release of relay 6H the polarity of the energy supplied from battery XIIB over line circuit XII to relay ZZER is changed from normal to reverse so that polar Contact |53 of relay ZEER is shifted from its normal to its reverse position to thereby extinguish the green lamp G of signal 22E and establish the circuit of the yellow lamp Y of this signal.

When the rear of the train vacates section 2T,

track relay ZTR picks up, but line circuit X is interrupted by track relay 3TR so that there is no change in the signals at this time.

When the train advances into section T, track relay ETR releases and interrupts the supply of energy from battery XIIB to line circuit XII so that relay ZEER is deenergized and its contact I3! establishes the circuit of the red or stop lamp R of signal 22E. In addition, on deenergi- Zation of relay 22ER its neutral contact I32 cuts off the supply of coded energy to the transformer XX'IT and effects the supply of steady energy thereto. On this change in the energy supplied to the line circuit XX relay 24ER is steadily picked up so that relay 24H remains picked up, while relay 24J releases so that the indication displayed by signal 26E is changed from green to yellow. Release of contact I5! of relay 24J vinterrupts the supply of coded energy to the transformer XXITT so that the eastbound signal next in the west of signal 24E is also conditioned to display its caution indication, and an eastbound train if approaching siding P would receive a yellow or caution indication at the signal next west of signal 24E, which would enable it to stop at signal 24E and enter siding P.

At this time coded energy from the transformer XIITT continues to feed to the relay 5WR so that relays 5H and 5J are picked up and condition signal 5W to display its green or clear indication.

When the rear of the train vacates section 3T, track relay STR picks up so that coded energy from the transformer XTT feeds to the relay IER and this relay supplies energy to the relays 4H and 4J to thereby cause signal 4E to display its green or clear indication. In addition, picking up of relays 4H and 4J effects the supply of coded energy to transformer XITI, but at this time line circuit XI is interrupted by track relay 4TR so that the coded energy does not feed to relay SER.

When the train advances into section 6T, track relay GTR releases and cuts olf the supply of energy from the transformer XIITT over line circuit XII to relay SWR. This relay is, therefore, deenergized and relays 5H and 5J release and establish the circuit of the red or stop lamp R of signal 5W.

When the rear of the train vacates section 11T, track relay ATR picks up so that energy from the battery XB is supplied to the line circuit X. At this time relay SWR is `deenergized so that its contacts Idil and MI are released and the energy supplied from the battery XB to the line circuit X is of reverse polarity. Relay IWR, therefore, is energized and its polar contacts II and IGZ occupy their reverse positions. Accordingly, the circuit of the yellow lamp Y of signal IW is established, While steady energy continues to be supplied to the transformer IXTI', and thus to the line circuit IX so that the westbound signal next to the east of signal IW is conditioned to display its yellow or caution indication.

When the train advances into section TI', track relay 'ITR releases and additionally interrupts the line circuits XI and XII.

When the rear of the train vacates section 5i?, track relay BTR picks up, but at this time line circuits XI and XII are both interrupted by track relay 6'IR so that picking up of track relay 5'I'R does not change the aspects of the signals.

When the train advances into section ZIT, track relay 2 ITR releases and interrupts line circuit XX to cut oif the supply of energy from the transformer XXTT to relay ZIIER. Relays 24H and 24J, therefore, release and condition signal 24E to display its stop indication, while release of these relays cuts off the supply of coded energy to the transformer XXITT and effects the supply of steady energy thereto with the result that the eastbound signal next in the west of signal 24E is caused to display its yellow or caution indication.

When the train vacates section 6T, track relay @TR picks up so that coded energy from the transformer XITT is supplied over the line circuit XI to relay EER, and this relay effects the supply of energy to the relays 6H and 6J so that they pick up and condition the signal 6E to display its green or clear indication.

When the train advances into section 22T, the track relay 22TH, releases and cuts off the supply of energy from battery XXB to relay ZIWR and this relay releases and conditions signal 2 IW to display its red or stop indication. In addition, release of relay ZIWR cuts off the supply of coded energy to transformer XIITT and effects the supply of steady energy thereto. At this time, however, line circuit XII is interrupted by track relays 2I'IR and ITR so that energy from the transformer XIITT does not reach relay SWR and signal 5W continues to display its stop indication.

When the train vacates section 17T, track relay ETR picks up so that energy from the battery XIB is supplied over the line circuit XI to relay SWR. This energy is of reverse relative polarity as the relay WR is deenergized and relay 5H is rel-eased. At this time, therefore, the polar contact I3? of relay SWR is shifted to its reverse position and the signal 3W is caused to display its yellow or caution indication, while as the neutral contacts Ifl and I4! of the relay SWR are picked up, energy of normal relative polarity is supplied over line circuit X to relay IWR and this relay conditions signal IW to display its green indication. In addition, relay IWR effects the supply of coded energy to the transformer IXTT so that coded energy is supplied over line circuit IX to thereby condition the westbound signal next in the east of IW to display its green or clear` indication.

When the train vacates section ZIT, track relay QITR picks up and ener-gy from the battery XIIB feeds to the relay ZEER and this relay conditions signal 22E to provide its green or clear indication.

As the train proceeds through the track stretch, the signals associated with passing siding P operate in the same manner as the signals associated with section Q and a detailed explanation of their operation is not necessary.

From the foregoing it will be seen that on movement of a train through the track stretch in either direction the equipment operates to provide adequate protection to prevent a following train from running into the preceding train.

Thus, when an eastbound train is in section 23T or 22T associated with the passing siding P, the signal ZilE displays its stop indication, while steady energy is supplied to the line circuit XXI so that the eastbound signal neXt to the west of signal ME displays its yellow or caution indication.

When an eastbound train is located in advance of signal 22E, this signal displays its stop indication, and steady energy is supplied to line circuit XX so that signal ZliE displays its caution indication. In addition, the eastbound signal next in the west also displays its caution indication so that a following train receives two `caution indications and a stop indication before reaching the first train.

When an eastbound train is located in advance of signal 6E, this signal displays its stop indication, while line circuit XII is interrupted so that relay 22ER is released and conditions signal 22E to also display a stop indication. In addition, the two eastbound signals in the rear of signal 22E display yellow or caution indications.

When the train advances beyond track section T, signal 6E continues to display its stop indication, While signal 22E is conditioned to display its yellow or caution indication, and coded energy is supplied to the line circuit XX so that the eastbound signals in the rear of signal 22E display green or clear indications.

When the train advances beyond signal E-E, signal 4E displays its stop indication, while signal 6E displays its caution indication and signal 22E displays its clear indication.

It will be seen, therefore, that the iirst signal in the rear of an eastbound train displays a stop indication and also that there is at least one signal displaying a yellow or caution indication so that a following train has ample warning of the presence of the rlrst train.

In like manner, protection is provided for westbound trains. When a westbound train is located f in advance of signal IW, this signal displays a stop indication, while steady. energy is supplied to line circuit IX so that the adjacent westbound signal in the rear displays a caution indication.

, When this train advances beyond signal 3W, I"

this signal displays its stop indication, while signal IW continues to display its stop indication until the train advances beyond section 6T at which time the aspect of signal IW is changed from red to yellow.

- When this train enters section 5T, signal 5W displays its stop indication, while signal 3W continues to display its stop indication until the train passes out of section 1T. When the train passes out of section 1T, signal 3W displays its yellow indication, while signal 5W continues to display its red or stop indication. The signals remain in this condition until the train enters section 22T. When this occurs, the signal 2IW displays its stop indication, while when the train vacates section ZIT, the indication displayed by signal 5W is changed from red to yellow, while that of signal 3W is changed from yellow to green or clear. The signal 5W continues to display its yellow or caution indication until the train vacates section 24T, at which time signal 23W displays its red or stop indication, while signal 2 IW displays its yellow or caution indication. From the foregoing it will be seen that when a westbound train passes through the track stretch, the rst westbound signal in the rear of the train will display a stop indication, while there is always at least one westbound signal in the rear of the train which displays a yellow or caution indication.

Operation of equipment on movement of trains in opposing directions through the track stretch rection arecontrolled far enough in advance of Vent a head-on collision between trains.

When an eastbound train is present in section 24T at the left of passing siding P, signal 23W is at stop to thereby prevent a westbound train proceeding beyond the passing siding, while signal ZIW is also at stop and signal 5W is at caution so that a westbound train has ample warning of the approach of the eastbound train.

When the eastbound train advances beyond passing siding P and enters section ZIT, signal 5W is placed at stop, while signal 3W is placed at caution. As soon as the eastbound train enters section 7T, signal 3W is also placed at stop and signal IW is placed at caution.

Similarly, when a westbound train is present in section I'I', the eastbound signal 2E is at stop, while the eastbound signal 4E is also at stop` and the signal 6E is at caution.

When the westbound train proceeds beyond the passing siding Q and enters section 4T, the signal 6E is placed at stop, while signal 22E is placed at caution. As soon as the train enters section 5T, signal 22E is placed at stop and signal 24EV is placed at caution, while the next eastbound signal to the west of signal 24E is also placed at caution. When the train advances into section 6T, signal 5W is placed at stop, while when the train advances into section ZIT, signals 22E and 24E are both at stop and the eastbound signal neXt in the west of signal ME remains at caution.

From the foregoing, it will be seen that this modicationoperates to provide an indication in advance of a train of the approach of the train so that trains moving in opposite directions will not collide head on.

It will be seen also that the modification shown in Fig. 3 like that shown in Fig. 1 has line circuits in which both alternating and direct current is employed and that one form of energy controls the signals for one direction of traflic and that the other form of energy controls the signals for the other direction of traino.

The modicationshown in Fig. 3 differs from that shown in Fig. 1 in that the two polarities of direct current are employed to provide two proceed indications, while coded and steady alternating current energy is employed to provide two proceed indications.

Although in this system alternating current energy of one code frequency together with steady alternating current energy is employed to provide the two proceed indications, the invention is not limited to this arrangement and it is contemplated that two code frequencies of alternating current might be employed to provide the two proceed indi-cations.

Although I have herein shown and described only three forms of railway signaling systems embodying my invention, it is understood that various changes and modifications may be made the-rein within the scope of the appended claims without vdeparting from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1. In combination, a stretch of railway track having a pair of track rails over which traffic moves in both directions, the rails of said track stretch being divided by insulated joints into a plurality of track sections including a rst, a second, a third and a fourth track section, a first signal governing entrance of trains moving in 

